An odd spell to Craft Invisible Illusions

Yep, you read that right. The idea is to create an illusion which is normally not able to be perceived by a human, and then a second spell which then allows the wizard to perceive the special effect. Such as an illusion using ultrasonic sound or ultraviolet light and the caster has a second spell which detects them.

Why? Well I was thinking about how an Ars Magica Magus might create their own heads-up system, or mark allies before battle, or a way to tag people they meet as significant. This way their tags are not readily readable by everyone, and the target need not know. Alternatively the illusion might almost match the true image of the target, which is then highlighted by a special Intellego spell.

The complexity in building a HUD is effect duration and memory. Effect duration can be solved by investing the effect into an enchanted device, which then maintains concentration and can be enhanced with greater penetration. Memory cannot, and this is why the spell creates a marker on the target so they can see the detail.

As a stand alone spell, intended to be used over a longer time period.

Paint with Invisible Brushstrokes

Creo Imagonem / Muto 20, R: Voice, D: Moon, T: Individual

This spell creates a simple visual illusion using tailored species which are not normally perceivable by humans.

(Base 1 to create a visual illusion, +2 Voice, +3 Moon, +1 moves with the target, +1 for complexity)

Paint with Invisible Sigils

Creo Imagonem / Muto 20, R: Touch, D: Sun, T: Group

This spell creates a simple visual illusion upon all members of the group touched, using tailored species which are not normally perceivable by humans. The sigil is is a simple coloured marking, up to a pace in any direction. The intent is to mark allied companions and soldiers before battle which allows them to be easily differentiated, but it may also be used to mark any group.

(Base 1 to create a visual illusion, +1 Touch, +2 Sun, +1 moves with the target, +1 for complexity, +2 Group)

Then the spell to perceive the typically invisible illusions.

Perceive the Brushstrokes of Invisible Paint

Intellego Imagonem 15, R: Personal, D: Concentration, T: Vision

Allows the caster to perceive any normally invisible illusion or “brushstrokes” created with the associated spell.

(Base 1, +1 Concentration, +4 Vision, +1 for complexity)

Ref: A discussion thread on the topic in the official Ars Magica forums. This and other spells can be found in the Grimoire of New Spells for Ars Magica.

Reworking an illusion spell for greater effect

Illusions are tricky things to adjudicate in a system which is as flexible as Ars Magica. Questions of adjustments for complexity, accuracy and detail in the conjured illusion all are reasonable however as there is a wide degree of variability in the allowances for complexity in the canonical spells, often the players themselves need to reach their own conclusions (which is generally a potential strength rather than weakness of the system in my opinion, but then I like the banter).

A good question was asked in the forums on “attacking with illusions” and I then started thinking about a more powerful version of a core spell which overloads the target’s senses. Overloading the senses of opponents is one of the easiest spells to leverage.


The Ars Magica rulebook Houses of Hermes: Societies, p68 has a spell called An Enemy Awash in the Pure Sigil of the Magus (CrIm15). By overloading the target’s eyes with visual sensations, this spell can blind the target for 2+ minutes, without using a Perdo requisite to physically “damage” the target. It is not always effective beyond one combat round, but it is still a very good spell. Particularly so because it is not an exceptionally high level spell, nor does it depend on the type of target, and it’s low level makes it potentially good for penetrating magical resistance.

So canonically overloading a sensory organ to the point of failure is very plausible. At level 15 for a Range: Sight spell it is also significantly better than blinding a target with Perdo Corpus which is many magnitudes higher.

Below are versions of that spell to overload many senses of one target, or the visual sense of a group of targets. And  most easy to learn for many Magi and it does not permanently damage the target.

An Enemy Immersed in a Sea of Stimulus

Creo Imagonem 25, R: Sight, D: Concentration, T: Part

This spell projects magical species at the target seeking to overload their senses of sight, hearing, and touch. The spell requires no Finesse check to target. The target may be disorientated for up to two minutes after the caster ceases concentrating (see HoH:S 68).

(Base 4, +3 Sight, +1 Concentration, +1 Part)

The effect is adjusted upward by one magnitude for each of hearing and touch, to create an effect which overloads the target’s sense of touch, hearing and sight (from base effect level 2 to base 4).

It is arguable how much more effective the spell effect would be when three senses are overloaded at the same time. In the original spell the target can shut their eyes to only be affected for a round, which seems less plausible for a spell which affects three senses. I suggest that the target is disorientated while the caster concentrates, and given the spell’s level that is not unreasonable.


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